The present invention relates to electrical circuit element measurement technology, and, more particularly, to methods and circuits for measuring high impedance elements.
Many electrical circuits require a high level of isolation for electrical components to ensure that these components aren't adversely affected by short circuits, electrical fields, magnetic fields, and the like. FIG. 1 illustrates an example where electrical isolation of measurement circuit components is important to obtain valid data. In particular, FIG. 1 is a diagram that illustrates circuitry for evaluating the concentration of particulate in a gas stream. A stack 105 has a gas that flows therethrough and contains particulate matter 110. A probe 115 is configured to extend into the gas stream and is charged through a triboelectric effect by the particulate matter 110 colliding with the probe 115. The triboelectric effect results in an signal being generated, which can be processed by signal processing circuitry 120 and provided as an input to a particulate matter analysis module 125 to evaluate the concentration of the particulate 110 matter in the gas stream.
The particulate matter 110 in the gas stream along with dust and other foreign debris can build up on surfaces of the stack 105 and/or the probe 115 and have the potential to affect the electrical characteristics of the probe 115. For example, build-up of debris adjacent to the probe 115 may create electrical paths to ground or other electrical circuits resulting in a signal output from probe 115 that is not representative of the concentration of the particulate matter 110 in the gas stream.